Abrasive belt



MY 15, 1946- A. L. BALL ABRASIVE BELT Filed June 29, 1940 @mi U m w l ma l www ATTORNEY.

Patented July 16, 1946 ABRASIVE BELT Albert L. Ball, Lewiston, N. Y., assignor, bymesne l assignments, to United Cottonl Products Comf ss.

pany, Fall River, Ma sachusetts Application June 29, 1940, Serial No. 343,105 l (Cl. Eil-188).

12 Claims.

This invention relates to the manufacture of endless fibrous Webswhich are substantially nonlamellar in structure and free from joints kor splices. More particularly, it relates to the manufacture of endless fibrous Webs, in which abrasive grain, adhesive binders and modifying agents are incorporated internally and/or externally of ythe fibrous web for the purpose of imparting specific properties to the entire, or to certain portions of, the resulting web. It also relates to the article produced by such-'a process.

Heretofore the practice in forming abrasive belts has been to out a strip of coated abrasive material of proper length and then splice the ends together to form a continuous belt. 'Iheresulting joints have proven objectionable, because they present points of potential weakness inthe belts and also interfere with accurate and smooth tracking of the belts in operation. Belts Yhave therefore often been made with liners or backings to 'give added strength and support to the belt as Well as to improve the tracking characteris-V tics of the belt. Such belts, in addition to the added cost, have been subject to loosening and parting of the laminations with consequent failure during use. Other belts, particularly Wide belts, have been'made `by using a spiral of nar-r rower material with the terminus portions of the belt material located remotely one `from the other.y in order to avoid any single point in the belt being completely traversed laterally by a splice.

As illustrative of the above and other diiliculties confronting those who make anduse endless belts, reference may behad to the abrasive grinding and polishing art. The present invention, for the purpose of convenience and simplicity of explanation, Will mostly be described and set forth as it is used in the abrasive art to which it is particularly well adapted, and to which it lends numerous improvements and advantages which will become readily apparent, although the invention is not necessarily limited thereto. Endless abrasive belts are Widely used in this field for polishing and grinding various surfaces. It is often desirable toabrade or polish expansive flat surfaces, in which case it is preferable to use extremely wide belts having av Width of 60 inches, '72 inches and even up to 100 inches. In addition to the objectionable features of jointed or laminated belts inherent in themselves and rval-V ready pointed out, splices or joints and other even slight irregularities in endless abrasive belts produce aws of various types.A in the Work being surfaced. Among such surface vblemislfiesordev fects so produced and attributable to a large eX-.

a corporation Vof Mastentv to ysplicing or joining of the endsj in endless belts are revolution marks or profile'mai-ksl which are'longitudinal scratches orY lines-pro` At other times the surface is scarred with dark spots or discol-` Furthermore, splices 'fonpoorly joined duced in the finished surfaceorations. laminations in a belt result inv uneven 'or' bumpy operation of an abrasive belt and .poori tracking y behavior, therebyfyieldingan objectionableunl evenness in the finished surface.`r For these vand f f other reasons it has long been lv-desired to obtain A spliceless, endless abrasive belts.

In accordance with the present :inventionend- "i less belts` are provided which are "continuousin forth above will become apparentv asthe desc tion ofthe invention proceeds herein.

Theinvention'm'ay be moreclearly understoo by reference to the1accompanying"drawing,fini` Which y Figure 1 is a verticalcrosslsection;largelydia grammatic, of anl apparatusffor'making endless belts or webs in accordance'Withthefteachings' of the" present invention;

Figures 2. 3, 4 and 5 'are' illustrative ofv'ariou's belt structures embodying the'present invention(` Figures 2a, 3a,`4a 'andfa are greatly enlar vertical cross-sections throughr longitudinal''fag# ments of the belts shown infFigures 2,3, 4 and', respectively, and are presentedl to` clearlyshow the freedom from any" distinguishable lamina# tions in the belts depicted.

Referring further to the apparatus shown l Figure l, the reference character`2` indicates fa' carder assembly consisting of a carding roll 3,

a stripper roll `4 `and 'a comb` 5 for removinggth'e fibrous carded membrane fro-mths roll"4'.` --The' carded membrane ,6' mavconsist of any animali vegetable or synthetic v-brous 4n'iatjerial capable of being'carded into yarn orsheet fo'rrnl *Among the fibres suggested for Y'use areV such -iiatural fibres as cotton, Wool, jute, flax and thelilejr any of the newer inorganic or organic synthetic libres ,such as fibrousf`=glass vor various resin'ous materials. The carded.' membrane isfed by grav# ity through an orice or Yslotf'l in the floorlion"2 er may have deckle edges for guiding theoncorning" toa mcvingcarrier belt 9 which' is slightly 'vvid thantherwidth ofthe deposited membrane web on to the traveling belt.f'-The ycarrier*belt is rotated about the supporting rolls' I0 andf'l'I-,f

either one or bothof which are adjustablehorizontadlfy, in order to permit slackening or tensioning offt'he belt at will. The carrier belt 9, preferably, should be porous in character and may be made `of 60 mesh bronze wire screening or smooth, sized canvas of open weave. The rate of deliyery of the carded web 6 and the speedof carrier belt 9 are synchronized by adjustment of thespeed of rotation of the carder roll and the carrier Ibelt 9, in Vorder that no appreciable strain its deposition.

around the peripheral surface of the carrier belt, is first deposited and then, as the succeeding layers are deposited, the action ofthe air currents and vibrating roll causethe fibres of the initial Vv1o or pull is exerted on the thin membrane during'.

The i-nitially deposited membrane or lap 6 is retained in place on the carrier belt 9 by afsup porting belt I2 duringthe process of buildingup ,the'brous web to vthe desired thickness:v The supporting belt I2 is mounted on a. system ofv .pulleys I3, l4,"l5, I5 anda plate l1 and driven' "impregnate the web with adhesive binder mateby suitable meansv (not shown) to operate at Y thevsame surface speed as that of the carrier belt andthe deposited membrane.

'from' contact with the'web. This may be accom# plished 'by lowering the entire Vsupporting belt, pulley and pressure plate assembly or by lateralv vmovement thereof. LVA suction box is'in'corporated inthe roll II at the 'point indicatedby the reference character I8 in orde'rto retain the web membrane in place as the direction of travel is changed: This action may be supplemented b'yvmeans of a doctor blade or air knife I9 which prevents the web from ad-` hering tothe surface'ofthe supporting belt.

, Fibres leaving'the carder assembly are arranged -in a generally parallel position whichis normally *1i-assumed as a result 'of the carding action. When ,deposited on the carrier 'belt in this state the libres vtake for the most partr a' position substan` tially^parallel to Vthe surface of the belt andpif undisturbed; would be matted down by any addi` tional layers anda laminated web produced which would be easily separated. It is highly desirable that an interlocking fibrous structure be produced in which many of the libres of each membrane will project upwardly at vacute or right angles to thesurface'off the web and not only intertwine with one another but` also`interlock and knit together with the bres ofthe succeeding layer;

For this reason means 'are provided to disturb the bresfrom their normally parallel positions and raise or up-end large numbers of them for'intery locking with the fibres 4of superimposed 'membranes.- `To accomplish this actionrv thepresent apparatus is provided with air boxes 20, connected to an air supply Yduct 12|', and positioned directly below the upper surface of the carrier belt 9 -so i,

as -to direct -a gentle flow of air or vother gas through the pores of the belt itself and through' the deposited membrane; VThis stream of air is supplied at low-pressure so as not toirupture' the membrane and` may be continuous or of a-pulsating nature. f -Additional currents of kair may be setv up above the carrier belt -surface to createY some alteration of the fibre direction before deposition of the membrane upon the belt. I Y

Further intertwimng and'interlocking of uneV iibres'may beproduced by a rotating beater roll 22 which is equipped withfprojecting fins and adapted to yset up a vertical vibration-of the car-.-

rier belt 9. 1 The amplitude of this Vvibration is' controllable ,and-the action is limited by a Vbaffle plate 23 located above the beltl and 'at apoint directly over the beater roll.

In the manufacture of an endless belt an initial layer of'carded fibrous web,sextending` completely;

y Means are prollidd forqucklydisengaging the supporting belt f layer to assume positions ideal for interlocking therewith. Thus each succeeding fibrous membrane Vis rmly intertwined with theV previously applied layer anda non-laminated web is produced. This operation is continued without interruption until a sufficient thickness of felted 'K web has been built upon the carrier belt, at which 'time the flow of fibrous material from the carder is stopped.

After a web of the desired thickness has been formed in the manner described it is ready to be compacted toa greater density for added strength, and at the same time it is usually desirable to rial to additionally strengthen it. The adhesive binder 4when applied to the web at this stage in the operations is usually applied in liquid form.

The web is compacted Vby* lowering the pressure roll 24 the desired amount and rotating the belt and supported web between supporting roll 25. Y

Application of the impregnating binder is usually carried out after compacting, although it is optional and may be applied earlier in the process;

Sometimes it is desirable to add the impregnant in increments or continuously between deposition of the various individual membranes, in which case any suitable device (not shown in the drawing) may be located somewhere along the path of travel of the web for applying the impregnating substance, which may be handled in the form of a liquid spray or a powdered spray, although other manners of placing the adhesive such as sifting it on the vbelt may be used. v

Referring now to Figure 1 ofV the drawing, after the web is compacted an impregnating adhesive is applied-in the following manner. A liquid;

contained inthe pan 29, is pickedvup Iby the roll 26 andapplied to the upper surface of the lbrous web 30 by the` transfer rolls 21,` 28 andthe pressure roll 24. Y Pressure is maintained between rolls 24 and 25-in order to distribute..the adhesive rimpregnated the rolls 24 and25 are raised and` lowered respectively, to release the belt, and the supporting belt system I2 lowered or moved away throughout the web until suiiicient has .been applied. After the belt has been Vcompacted Jand laterally to clear the belt. The resulting endless web may then be removed by slackening the rolls IB and Il and dried and cured elsewhere in any well known manner, or the web may be dried while still rotating under tension upon the carrier belt,- and later removed ready for use.V

imodied endless belts. Such belts areformed by the addition of abrasive' grain or other nonbrous modifying agents'to the surface of the beltbeforev or afterA compacting and/or the incorporation of suchmaterials'into the interior of the belt during its. fabrication.

pressure roll 24 andv Accordingl to one modification oftheherein described method of making abrasive belts, a layer of adhesive and abrasive grains may be applied immediately after the fibrous web has been built up and compacted as abovedescribed. An additional coating of adhesive is applied to the outer surface of thel belt by means of the glue pan 29, rolls 26, 21, 28, 24 and supporting roll 25. After this, abrasive glrains are applied from the supply bin 43, control hopper 3| and adjustable distributing roll 44 onto the adhesive coated surface of the web. The abrasive coated belt is then dried or cured sufficiently to secure the grain in place and a further sizing coat of adhesive is applied by glue rolls or sprayed, as desired. In certain instances, it is more desirable to apply the surface coating of adhesive and abrasive grain before the web is compacted.' We have found that this causes the abrasive grains to be more firmly held in place because of the 'fact that they arepartially lodged between the interlocking fibres of the upper part of the web.

Another modification of the present invention involves the stepof incorporating abrasive grain in the interior of the belt. This feature is especially applicable to the making of abrasive polishing belts in which a relatively line grit grain is used. According to this method of making endless belts the abrasive is incorporated internally of the belt by adding the grain to the deposited membranes during the process of building up the Web. Figure l shows apparatus for carrying out this step and includes a bin 32. for holding abrasive grain, a controlhopper 33. and adjustable feed roll 34 for lfeeding a thin stream of abrasive grainonto the deposited membrane.l

After the iirst few layers of fibrous membrane have been deposited on the carrier belt and the fibres suitably interlocked by operation of the vibrating and air pulsating equipment previously described, the feed roll 34 is adjusted to feed a thin stream of abrasive grain 35 onto the d eposited membrane. Additional membrane is deposited over the top of the layer of grain and the operation continued by deposition of grain between the individual laps, the fibres of which intertwine and weave about the grain to securely hold it in place. To assist in holding the grain firmly, an adhesive binder may be added by means of one or more spray nozzles 36 positioned above and across the top surface of the belt. This adhesive may be a liquid glue binder. a synthetic or natural rubber adhesive, a resinous binder in a liquid solvent. or a powdered adhesive. As an alternative manner of incorporating a binder with the grain, the grain may be treated by applying a coating of a binder prior to vfeeding it onto the belt. After the fibrous web containing the abrasive grain with or without binder, has been built up to therequired thickness, the belt is compacted as earlier set forth. A further surface coating of grain may be added if so desired4 before drying and curing the belt.

The endless belts may be further modified by the application of various modifying agents during various stages of the building up of the belt in the same way in which the adhesive is added and in any required amount. For example, the belt can be waterproofed by applying a continuous spray of waterproofing agent during the laying down of the membrane upon the carrier belt. Again, antifriction ingredients, such as graphite, soapstone and the like, may be incorporated in those laps or membranes making up the portion of the belt immediately adjacent the inner surface, and at any stage 'in the' manufacture flexibilizing agents may be similarly incorporated'.

Flexibilizing agents may be incorporated in a portion of the web or distributed throughout, de-

pending upon the type of product desired. Im-

pregnation with a long oil synthetic resin varnish, such as that made by Pratt and Lambertand designated by them as N0. 1767, produces a strong and very flexible web. Suiiicient varnish should 'be incorporated so that it will comprise 20% to 40% by weight of the impregnated fibrous .to leave a dry residue of 20% to 40% by weight,

and then the impregnated material cured from 2 to 4 hours at a temperature of 250 to 280 F.

Various plasticizers, such as glycerine, dibutylphthalate, and the like, may be added to the varnish impregnating agents in order to increase their exibility. The quantity 0f such material employed will depend upon the desired flexibility characteristics of the finished product and may in some instances amount to 40% of the combined weight of the varnish and plasticizer.

. Figure 2 and Figure 2a which is a greatly enlarged fragmentary cross-section of Figure 2 show an endless beltmade according to the above procedure, and in which the individual bres 3'lfof the various membranes have been interlocked so as to form a uniform non-lamellar structure impregnated throughout with a binder material 38.

Figure 3 and accompanying Figure 3a show a modified endless belt similar to that shown in Figures 2 and 2a. However, a surface coating of adhesive 39 and abrasive grain 40 has been ap-Y brous structure of the belt in non-lamellar form.

Figures 5 and 5a embody the features of both belts'shown in Figures 3 and 4 in the same belt, and in'addition show the wayin which various modifying agents, such as antifriction agent 42 has been applied to specific portions of the belt to impart desired properties to all or part of the belt.

It is sometimes desirable to produce a serrated. embossed, spiral, uted or otherwise patterned outer surface on the endless belt after the structure has been impregnated. This can be accomplished by means of a pairof rolls (not shown in the drawing) adjustably mounted one above and one below the belt. The roll in contact with the outer belt surface is suitably patterned or embossed for the purpose at hand. The desired pattern is impressed in the outer surface of the belt by bringing the patterned roll into Contact with the beit with sufficient pressure to produce an embossed. surface thereon.

Either or both rolls may be temperature controlled'to provide the proper conditions for molding a surface upon the impregnated structure. For example, cold rolls may be used when a glue, which has been used to impregnate the belt has gelled and become almost dry, while hot rolls should be used to treat a synthetic resin impregnated belt after the resin has dried throughly aangeeft 7 Y and has. been advanced partially l,tovvardt its final stag'eofcure.r i v -v -y' A'further modification of the presentinvention provides for Ythe production of endless belts, `of great tensile strengthv and resistance to crosswise tearing, for use under very severe forms of abrad- FigureV l. The inclusion of the reinforcing strands' may be continuous from `.the Astart to the nish of the beltl constructing operation, or it may be delayed at the start of the operationand interrupted prior tothe completion of the article in order 3toV locate the reinforcing elements WithinY the structure. A Wave form 'type of reinforcement is produced by oscillating the framework which carries the spools or reels of stranded material.

As has been pointed out earlier herein, one of the particularly important features of the present invention isthe provision of an endless belt structure Ywhich isv continuous and free from joints oi?v any kind. Another` important characteristicv of the present invention is Vthe provision of endless belt structures in which various desired properties may be imparted to specific portions of the belt without resort to individualr layers or laminations. andin which such characteristics may b uniformly set up Within the belt. i

Having described and explained the invention it is desired to claim: Y Y l l. The method of making a continuous endless and jointless felted brous web of homogeneous non-lamellar cross-sectionrwhich comprises removing -a thin continuous membrane of ,fibrous materialfrom a carder, aerodynamically agitating said membrane to disturb and up-end the ends of the individual fibers from their normally parallel position Without rupture of the membrane, feed-v ing Vsaidfmembrane upon a moving --endless support, retaining the initially deposited membrane upon said support -While repeatedly passing said endlesssupportowith the initially depositedmem brane beneath the carder 'to receive additional superimposed membranous layers While the ends of the individual bers of the deposited mem# brane'on the moving support are up-ended for interlocking with the bers of that portion of the membrane being deposited to such anextent that the fibers of adjacent membranous layers interengage and interlock suiciently to produce a homogeneous non-lamellar structure, continuingV the deposition of said .continuous membrane under said conditions for 'interlocking and Without interruption of the flow of membrane from the carder Vuntil a jointless and endless web of the desired thickness is formed on the endless support, breaking the flow of membrane from the carder and removing the resulting brous web from said support. l

2. The-method of Vmaking a continuous endless and jointless felted fibrous web of homogeneous non-lamellar cross-section which comprises removing a thin continuous membrane of fibrous material from a carder, aerodynamically agitating'said membrane to disturb and up-end the ends 8,1 of the individua-l fibers fromtheir normally parallel position Without rupture of the -mem'brane,l feeding said membranel onto a moving endless support, agitating the deposited membraneto fur- Y ther raise the ends ofa' `number of individual libers, retaining the additionally 'deposited membrane upon the' support While repeatedly .passingsaid Vendless support with the. initiallydeposited membrane beneath `the carder lto vreceive additional superimposedfmembranous Vlayers while the ends of the individualfbers oft-the deposited membranousv material on the'moving support are maintained -upeendedfor -interlookinggwith -the fibers of that portion ofthe membrane; Vbeing de posi'ted to such an extentl that-the bers-ofthe' adjacent membranous layers are l interengaged and interlocked suiciently-toproduce a homoge`v neous non-lamellar' structure, continuingA the deposition of said Vconi'.- inuou s:membrane underY Vsa'id conditions for Ainterlocking and Wit-hout' interruption of the ow of membrane fromthe carder until'a jointless and endless-Web of fibrous material of the desired thickness isvformed fon the'endless supportfbreaking the ovv of :mem-- brane from the carder and removing the resulting fibrous web from said support; f j

3 The method of making- Va continuous endless and joint'lessfelted brous webv of homogeneous non-lamellar cross-sectionwhich` comprises re' moving a thin continuous 4membrane of brous material from'a carder, aerodynamically agitating said membrane to disturb and up-endthe ends of theindividual fibers from their normallyparallel position Without ruptureof the membraner feeding said membrane upon a -moving endless support, agitating the depositedmembraneto iur-V ther raise the ends of a'number of the individual fibers, retaining theinitially deposited membrane upon the support While repeatedly passing said endless support With-the-initially deposited-mem branel beneath the carder to receive additional superimposed membranous vlayers -While the Aends of Athe individual vbers of v the deposited mem-v branous layers on the moving support are -maintainedup-ended for interlocking. -With the fibers of the membranous layer being deposited-to such an e'xtentthat the bers off adjacent membranous layers interengage tand. interlock 4suiiiciently --to produce. .a homogeneous .non-lamellar, structure, continuing the deposition of said continuous meme brane under said conditions for interloking and Without interruptionl of-.the flow. of Ymen'ibrane from the carder until a joiritlessv and yendlessweb of brous material of the desired thickness ris formed on the endless,supporhbreaking ,the iiovv of membrane from the Carden impregnating the fibrous web with an adhesivebinder,l compacting the impregnated web and removing the resulting Web-from saidsupport, ,v

4..The method of making a `continuous endless and jointless felted viibrousvvebof homogeneous non-lamellar cross-section YWhich comprisesremoving a thin continuouslmembrane .ofiflbrous material from a, carder,Y ,feeding said vmembrane onto a moving endless support and aerodynamically agitating said membrane to remove theends of the individual fibers from theirnormally parallelpositionand to raise a number 0f `the ends of the fibers from the plane of said membranelr'e-L taining the initiallyv depositedmembrane Aupon the support While repeatedlypassing said endless layers, continuing the floW of membrane from the carder until a web of fibrous material of the desired thickness is built upon the endless support, meanwhile agitating the deposited membrane on the moving support to up-end and render the fibers thereof receptive for interlocking with the fibers of the membranous layers being deposited to such an extent that the fibers of adjacent membranous layers interengage and interlock sufficiently to produce a homogeneous nonlamellar structure, then breaking the flow of lmembrane from the carder, compacting the resulting fibrous web and removing it from the endless support.

5. In the method of making a continuous endless web of fibrous material according to claim 4, the step of applying abrasive graintofsaid fibrous web during the process of making the web.

6. In the method of making a continuous endless web of fibrous material according to claim 3, the step of applying abrasive grain to the outer surface of said fibrous web.

7. The method of making a continuous endless and jointless felted fibrous web of homogeneous lnon-lamellar cross-section which comprises feeding a thin continuous membrane of fibrous material from a carder onto the upper surface of a moving endless support, aerodynamically agitating the membrane to remove the ends of the individual fibers from their normally parallel position and to raise a number of the ends of the fibers from the plane of said membrane to an up-ended 'position suitable for interlocking with the fibers of subsequently deposited membranous layers, retaining the initially deposited membrane upon the support and superimposing additional fibrous membranous layers upon the initially deposited membranous layer, simultaneously applying abrasive grain and adhesive binding materials between successive layersvof the membranous material, meanwhile agitating the deposited membranous layers on the moving support to upend them and render the fibers thereof receptive for interlocking with the fibers of the membrano us layer being deposited to such an extent that the fibers of adjacent membranouslayers interengage and interlock sufficiently to'produce a homogeneous non-lamellar structure, continuing the deposition of said continuous membrane under said conditions for interlocking and without interruption until a jointless and endless web of the required thickness is formed, severing the flow of fibrous membrane from the carder, applying a final surface coating of abrasive grain and adhesive binder to the outer surface of said fibrous Web, compacting the web and removing it from the endless support.y

8. A continuous endless, jointless belt of felted fibrous materials comprising a plurality of thin 10 cardable fibrous laps the width of each membranous lapbeing co-extensive with the Width of the belt, a number of the fibres of each individual lap being raised from the plane of said lap to an upended position'so as to be interlocked with the fibresof adjoining laps to such an extent that the endless belt presents a homogeneous non-lamellarv cross-section.

9. A continuous endless, jointless beltA of felted fibrous materials comprising a plurality of thin cardable fibrous laps impregnated with an adhesive binder and being'further characterized by a number of the fibres of each individualY lap being raised from the plane of said lap to an up-ended position so as to be interlocked lwith the fibres of adjoining laps to such an extent that the belt presents a homogeneous non-lamellar cross-'section the width of each membranous lap being co-extensive with the Width of the belt.

the fibres of the adjoining laps to such an extent that the belt presents a homogeneous non-lamellar cross-section. Y

11.` A .continuous endless, jointless belt consistingV of a web comprising a plurality of laps of cardable fibrous materials impregnated with an adhesive binder and having abrasive grain distributed internally of the belt and an external coating of abrasive grain adhesively secured to the outer surface of the belt said web being further characterized by a number of the fibers of each individual lap being raised from the plane of said web to an up-ended position so as to be interlocked With the fibers of the adjoining laps to such an extent that the belt presents a homogeneous non-lamellar cross-section.

l2. A continuous endless, jointless belt consisting of a Web comprising a plurality of lapsA of cardable fibrous materials, the Width-of each of the said laps being co-extensive with the Width of the belt, said belt being impregnated with an adhesive binder and having anl external coating of abrasive grain adhesively secured to the outer surface of the belt, the web structure of said belt being further characterized by having a number of the fibers of each individual lap raised from the plane of said lap to an up-ended position so as to be interlocked with the fibers of the adjoining laps to such an extent that the resulting web structure presents a homogeneous nonlamellar cross-section. V

ALBERT L. BALL. 

